Glutathione: The Master Antioxidant Keeping Your Cells in Check Vitall Glutathione is the body's primary internal antioxidant, made using the amino acid cysteine, and it helps protect cells from oxidative stress. Beyond detoxification, research shows glutathione is involved in thyroid hormone metabolism, Role of glutathione in oxidative stress. During oxidative stress there Download Scientific Diagram L Glutathione vs. oxidized vs. Reduced Glutathione Antioxidant function of glutathione. GST: glutathione transferase; Download Scientific Diagram Glutathione: The Body's Master Antioxidant Explained